Two-stage type of electric dust arrester

ABSTRACT

A two-stage electric dust arrester having a charging stage and a collecting stage arranged in succession within a chamber defined by a casing. The charging stage includes a pair of charging electrodes spaced apart laterally of the path of flow of dust through the chamber. The collecting stage, located downstream includes a collecting electrode having a pocket extending along its length with an open face aligned with the space between the charging electrodes in the direction of movement of dust through the chamber. A high voltage DC source connected to the charging and collecting electrodes creates a field to accelerate dust particles as they move between the electrodes and for attracting the particles into the pocket.

United States Patent [191 Shibuya et al.

TWO-STAGE TYPE OF ELECTRIC DUST ARRESTER Inventors: Akira Shibuya,Tokyo; Susumu Takayama, Saitama; Yoshiiumi Nitta, Yokohama; KazuhikoSendai; Masaharu Yana, both of Tokyo, all of Japan Ishikawajima-HarimaJukogyo Kabushiki Kaisha, Chiyoda-ku, Tokyo-to, Japan Filed: July 2,1973

Appl. No.: 375,801

Assignee:

U.S. Cl 55/123, 55/129, 55/130, 55/138, 55/139, 55/152, 55/154 Int. ClB0ld 3/12, BOld 3/45, B0ld 3/41 Field of Search 55/123, 129, 130, 13s, 2

References Cited UNITED STATES PATENTS Schmidt Penney Werner GreyBradley .I 55/130 FOREIGN PATENTS OR APPLICATIONS 519,391 5/1953 Belgium55/130 840,853 7/1960 Great Britain.... 313/531 999,051 7/1965 GreatBritain.... 55/152 1,198,881 7/1970 Great Britain.... 55/152 714,8219/1931 France 55/447 1,268,819 6/1961 France 55/156 448,504 7/1928Germany 55/130 471,795 2/1929 Germany 55/130 45-29719 9/1970 Japan55/154 215,135 11/1941 Switzerland l. 55/137 Primary Examiner-Dennis E.Talbert, Jr. Attorney, Agent, or Firm-Price, Heneveld, Huizenga & Cooper[5 7] ABSTRACT tending along its length with an open face aligned withthe space between the charging electrodes in the direction ofmovement'of dust through the chamber. A high voltage DC source connectedto the charging and collecting electrodes creates a field to acceleratedust particles as they move between the electrodes and for attractingthe particles into the pocket.

14 Claims, 10 Drawing Figures VVVVS/ MAM Eli

PATENTEHAPR 16 m4 SHEET 2 0F 3 TWO-STAGE TYPE OF ELECTRIC DUST ARRESTERThe present invention relates to an electric dust ar rester for use inremoval of dust contained in an exhaust gas discharged from a bakingapparatus or kiln for limestone, cement and the like, a combustionapparatus for coal, petroleum and the like, or other exhaust gassources.

More particularly, the present invention relates to improvements in atwo-stage type of electric dust arrester consisting of a charging stagefor charging the dust in the exhaust gas by making use of a coronadischarge and a dust collecting stage disposed downstream of saidcharging stage for separating the charged dust from the exhaust gas.

The above-referenced two-stage type of electric dust arrester has anexcellent feature over the so-called single-stage type of electric dustarrester comprising a corona discharge electrode and a dust collectorelectrode disposed opposite to the former in that even if the apparentresistivity of the dust is as high as IO Q-cm the dust collection can beachieved without being accompanied with anomalous phenomena such as, forexample frequency of spark, inverse ionization, etc.

However, upon removal the dust accumulated on the dust collectorelectrode as by hammering, once the accumulated dust is dispersed againinto the exhaust gas, in the case of the single-state type of electricdust arrester, the recharging of the dust particles is achievedimmediately and is collected by the dust collector electrode. In thecase of the two-stage type of electric dust arrester there is adisadvantage that the dust particles are admixed into the exhaust gaswithout being recharged and thus discharged to the exterior.

A principal object of the present invention is to make it possible tocollect the dust particles without exposing the particles to the exhaustgas flow, even in the case of dust having an apparent resistivity equalto or higher than lO 'O-cm, or even upon removal of the dust which hasonce accumulated on the electrode as by hammering. I A second object ofthe present invention is to intensely charge the dust particles in theexhaust gas by making said particles contact directly to the coronadischarge electrode. 1

A third object of the present invention is to adjust the flow of theexhaust gas by means of the electrode and 7 thereby eliminate the properflow adjusting means.

A fourth object of the present invention is to provide double contactbetween the exhaust gas containing dust particles and the corona ions inparallel and antiparallel flows and thereby uniformly charge the dustparticles in the exhaust gas.

A fifth object of the present invention is to lower the temperature atthe opposite electrode and thereby prevent the inverse ionizationphenomena.

A sixth object of the present invention is to cause all the charged dustparticles to move towards the inlet of the pocket of the collectorelectrode.

A seventh object of the present invention is to capture the charged dustparticles in a space in front of the collector electrode, separate themfrom the exhaust gas by making use of a gravity, and thereby make themdrop away.

According to the present invention, a two-stage electric dust arresterincludes a charging stage and a collecting stage arranged in successionwithin a chamber defined by a casing, from an inlet to an outletthereof. The charging stage includes at least a pair of chargingelectrodes spaced apart laterally of the path of flow of dust throughsaid chamber. The collecting stage includes collecting electrodesaligned with the space between the charging electrodes in the directionof movement of dust through said chamber from the inlet to the outlet.Pockets are formed in the collecting electrodes and extend lengthwisethereof, the pockets have an open face directed upstream toward thecharging electrodes to receive dust particles. A high voltage DC sourceof electrical energy is connected to said charging and collectingelectrodes for creating a field to accelerate dust particles as theymove between said charging and collecting electrodes and for attractingthe particles into the pockets of the collecting electrodes.

The present invention will be more fully understood from the followingdescription of a number of embodiments of the two-stage type of electricdust arrester illustrated in the accompanying drawings, in which:

FIG. 1 is a schematic side view showing an outline of the two-stage typeof electric dust arrester according to the present invention,

FIG. 2 is an enlarged plan view of the same,

FIG. 3 is an enlarged perspective view of a part of the apparatus inFIGS. 1 and 2,

FIG. 4 is a plan view showing a modification of the part shown in FIG.3,

FIG. 5 is a schematic plan view showing another em bodiment of thepresent invention,

' FIG. 6 is an enlarged plan view of a part of the apparatus in FIG. 5,

FIG. 7a through 7y, respectively, show alternative embodiments of a partof the electrodes shown in FIG.

FIGS. 8 and 9, respectively, are plan views illustrating furthermodified embodiments of the invention, and

FIG. 10 is a plan view showing a modification of a part of the apparatusin FIG. 9.

The two-stage type of dust arrester illustrated in FIGS. 1 and 2,comprises a charging stage A and a dust collecting stage B arrangedwithin a casing 1 in succession from an inlet 2 of the casing towards anoutlet 3. In addition, beneath the casing 1 are provided a hopper 4 fordust and a transfer conveyor 5, and further in the proximity of theinlet 2 are provided guide blades 6.

The charging stage A consists of angle-shaped corona discharge orcharging electrodes 9 having a contactor 8 with sharp tips 7 fixedlysecured thereto and rodshaped opposite electrodes 10 disposed downstreamof discharge electrodes 9. Corona discharge electrodes 9 and oppositeelectrodes 10 are arrayed in multiple at intervals along the respectiveplanes transverse to the flow of exhaust gas.

The dust collecting stage B consists of elongated rodshaped drivingelectrodes 11 extending in the vertical direction and rod-shapedcollector electrodes 12 disposed downstream of the driving electrodes.The driving electrodes 111 are arrayed in multiple at intervalsproviding gap spaces 13 along a plane perpendicular to the direction ofthe exhaust gas flow. The collector electrodes 12 are also arrayed inmultiple at an interval along a plane transverse to the exhaust gasflow. An elongated pocket 14 is formed within collector electrode 12extending in the lengthwise direction. An inlet of pocket 14 is disposeddownstream of the gap space 13 formed between adjacent drivingelectrodes 11 and is directed towards gap space 13.

A high voltage DC source 16 is connected across the corona dischargeelectrodes 9 and opposite electrodes 10 and also across the drivingelectrodes 11 and the collector electrodes 12 via conductors 17 and alimiting resistor 18 as shown in the figures.

In operation, the exhaust gas discharged from an exhaust gas source (notshown) flows from gas inlet 2 through guide blades 6, charging stage Aand dust collecting stage B to gas outlet 3. The dust particles floatingin the exhaust gas are charged by the negative ion flow directed fromcorona discharge electrodes 9 to opposite electrodes 10.

Since the corona discharge electrodes 9 illustrated in FIGS. 1 and 2 areformed in an angle-shape crosssection and their comer edges are directedupstream, the exhaust gas flow is temporarily choked upon passingthrough the gap spaces between the corona discharge electrodes 9. Thedust particles in the exhaust gas are caused to contact the electrodesso that they are intensely charged in a short period of time.

The charged dust particles directed into the dust collecting stage B aredriven from driving electrodes 11 toward collector electrodes 12. Inparticular, since a high voltage DC source is connected across drivingelectrodes 11 and collector electrodes 12, the charged dust particlesare conveyed to within the pockets 14 of the collector electrodes 12.Because of the DC electric field established between electrodes 11 and12, dust collects on collector electrodes 12. The collector electrodes12 are applied with mechanical shocks as by hammering, and the dust thentorn off the electrodes 12 falls through the space in the pockets 14,reaches the conveyor 5 via the hopper 4, and then is discharged to theexterior. Therefore, the exhaust gas passing through the dust collectingstage B is converted to a clean gas containing no dust, and then led tothe outlet 3.

While the corona discharge electrodes 9 were formed, in theabove-described embodiment, in an angle-shape having a contactor 8 withsharp tips 7 fixedly secured thereto, the same function and effect canbe expected as shown in FIG. 4 by employing corona discharge electrodes9' of angle-shape having a contactor 8 and a plurality of needle-likeprotrusions 7' mounted at a predetermined interval in the lengthwisedirection along the rear edges on both sides of the angle-shaped body.

In the two-stage type of electric dust arrester illustrated in FIGS. 5and 6, the component parts designated by the same references bearing theprime designation as those in FIGS. 1 and 2 achieve the same functions.Reference numeral 19 designates an arcuated field forming surfaceprovided on each side of the rod-shaped driving electrode 11 having anarcuated transverse cross-section, the open end 20 of said drivingelectrode 11' being directed downstream. Driving electrodes 11' shown inFIGS. 5 and 6 are distinguished from those shown in FIGS. 1 and 2 inthat the configurations of the transverse cross-section are differentfrom each other and in that on each side of open end 20 is formed a DCelectric field forming surface 19 of arcuated shape.

Gap spaces 13' formed between DC electric field forming surfaces 21 ofarcuated shape of the adjacent driving electrodes 11 are disposed so asto oppose the inlet openings 15 of the collector electrodes 12 definedby field forming surfaces 21 formed on the respective sides of collectorelectrodes 12' which are provided downstream of driving electrodes 11.The width of the inlet openings 15' is broader than that of gap spaces13'.

The negatively charged dust. particles conveyed to the narrow regionsbetween respective adjacent driving electrodes 11 in dust collectingstage B are, due to the negative polarity of the potential on drivingelectrodes 11, repulsed by driving electrodes 11, concentrated by theelectric field between the driving electrodes 11 and collectorelectrodes 12' toward collector electrodes 12' which are maintained at apositive potential and collected in pockets 14' of electrodes 12.

Since the DC electric field is established toward the inner side of thecollector electrode 12' as shown by dotted lines in FIG. 6, almost allof the dust particles in the exhaust gas which are moving along thelines of electric force, are conveyedtoward the inner side of pocket 14in the collector electrode 12'.

FIGS. 7a through 7y illustrate examples of modified cross-sectionconfigurations of driving electrodes 11' and collector electrodes 12 inthe two-stage type of electric dust arrester shown in FIG. 5.

The corona discharge electrodes 9 in the two-stage type of electric dustarrester shown in FIG. 8 are similar to those shown in FIG. 2, butanother set of corona discharge electrodes 22 are disposed downstream ofopposite electrodes 10 in such manner that the apex edges of theangle-shaped bodies may be directed in the opposite direction to that ofcorona discharge electrodes 9. In addition, extending through theopposite electrodes 10 are formed passageways 23 for liquid coolant suchas, for example, cooling water. Water feed and discharge pipes (notshown) are connected to passageways 23. The other component parts inFIG. 8 designated by the same reference numerals as those shown in FIG.2, also achieve the same functions.

In operation, the dust particles in the exhaust gas flowing through thecasing 1 are at first charged as moving along with the ionic wind causedby the corona discharge and emitted from the corona discharge electrodes9 towards the opposite electrodes 10, subsequently they are charged asmoving inversely in the direction of the ionic wind flowing from theother set of corona discharge electrodes 22 towards the oppositeelectrodes 10, and thereby the dust particles can be charged uniformly.In addition, the liquid coolant such as water flowing through thepassageways 23 within the opposite electrodes 10 serves to lower thetemperature of the dust layer adhered to the electrode surface andthereby greatly reduce the electric resistivity of the same, so that theinverse ionization phenomena caused by the dust adhered to the electrodesurface may be eliminated.

In the two-stage type of electric dust arrester illustrated in FIG. 9,sorption electrodes 24 are provided at the center of the pocket 15 inthe collector electrodes 12 and applied with a potential of the samepolarity as the rod-shaped collector electrodes 12. The radius ofcurvature in the cross-section of the sorption electrodes 24 is smallerthan that of the field forming surface 21 on each side of the collectorelectrodes 12.

Sorption electrode 24 is disposed substantially on the center line ofgap space 13 formed between adjacent driving electrodes 11, in suchmanner that the extreme edge of the field forming surface of sorptionelectrode 24 istangent to the plane including the extreme edges of theelectric field forming surfaces on the respective sides of the collectorelectrodes 12. The other component parts designated by the samereferences as those described with reference to the precedingembodiments, achieve the same functions.

Inthis embodiment, a first uneven DC electric field as shown by dottedlines is established between the electric field forming surfaces 19 ofdriving electrodes 11 and electric field forming surfaces 21 ofcollector electrodes 12. Simultaneously a similar intense DC electricfield is established between electric field forming surfaces 19 andsorption electrodes 24. Dust particles passing through gap spaces 13between adjacent driving electrodes 11 are driven toward collectorelectrodes 12 by the first DC electric field and the intense DC electricfield to be concentrated at and adhered to sorption electrodes 24 andalso to be adhered to the inner surface of collector electrodes 12.

The dust adhered to the sorption electrode 24 grows gradually to form adust layer, which peels off by applying mechanical shocks or vibrationsas by intermittent hammering, and falls into the hopper 4 to becollected therein. Then the partly dispersed dust particles adhere tothe collector electrodes 12. The dust particles dispersed upon hammeringthe sorption electrodes 24 start to disperse substantially from thecenter of the inlet opening of the collector electrode 12, and areentirely transferred to the inner surface of the collector electrode 12and thereby completely collected.

FIG. 10 shows schematically a part of a modification of the two-stagetype of electric dust arrester illustrated in FIG. 9, in which an ACvoltage source 25 is connected across driving electrodes 11 andcollector elec trodes 12. In this case, because the AC electric fieldestablished between driving electrodes 11 and collector electrodes 12, apart of the charged dust particles are captured in the space betweenthese electrodes to be prevented from moving further, and under thecaptured condition the charged dust particles fall down to be collected.

It is intended that the scope of the present invention should not belimited to the preferred embodiments described above and illustrated inthe accompanying drawings. All modifications employing the principles ofthe invention are therefore considered as included in the appendedclaims unless these claims by their language expressly state otherwise.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

l. A two-stage type of electric dust arrester comprising a chargingstage and a dust collecting stage arranged in succession within a casingfrom an inlet of said casing towards'an outlet thereof, characterized bythe provision of:

a. a collector electrode disposed downstream of a gap space formedbetween adjacent driving electrodes in said collecting stage, saidcollector electrode having a pocket formed therein extending in thelengthwise direction, the inlet opening of said pocket being directedtowards said gap space, and

b. a high voltage DC source for establishing an electric field such thatcharged dust particles are driven in said electric field from saiddriving electrode toward said inlet opening of said pocket in saidcollector electrode.

2. A dust arrester as defined in claim 1, further characterized bycorona discharge means in said charging stage, said corona dischargemeans including a plurality of spaced apart rod-shaped electrodes eachhaving a body of angle-shaped transverse cross-section, the apex edgesof said angle-shaped body being directed toward said inlet of saidcasing, the rear edges of said angleshaped bodies being formed withsharp tips; and a plurality of opposite electrodes disposed downstreamof said corona discharge electrodes.

3. A dust arrester as defined in claim 2, further characterized in saidopposite electrodes having passageway means formed adapted forconnection to a coolant source.

4. A dust arrester as defined in claim 1, further characterized incorona discharge electrodes disposed in front and rear stages in saidcharging stage along the flow path of dust containing gas through saidcasing and opposite electrodes positioned between said front and rearstages of said corona discharge electrodes.

5. A dust arrester as defined in claim 1, further characterized in thatsaid driving electrodes and said collector electrodes are formed withpockets extending in their lengthwise direction; the side edges of saidpockets providing electric field forming surfaces of circularcross-sectional configuration, said pockets in said driving electrodeshaving inlet openings therein directed toward said collector electrodes,and said pockets in said collector electrodes having inlet openingsdisposed downstream of said gap space formed between said adjacentdriving electrodes.

6. A two-stage type of electric dust arrester comprising a chargingstage and a dust collecting stage arranged in succession within a casingfrom an inlet of said casing towards an outlet thereof, characterized bythe provision of:

a. a plurality of rod-shaped collector electrodes disposed downstream ofa plurality of rod-shaped driving electrodes said driving electrodesbeing spaced apart having gap spaces formed therebetween, said collectorelectrodes having pockets formed therein extending in the lengthwisedirection; said pockets having inlet openings directed toward said gapspaces,

b. rod-shaped sorption electrodes positioned at said inlets to saidpockets of said collector electrodes; and

c. a high voltage DC source having a negative terminal connected to saiddriving electrodes and a positive terminal connected to said collectorelectrodes.

7. A dust arrester as defined in claim 6, further characterized in thatsaid driving electrodes are formed with pockets extending in theirlengthwise direction, said pockets having inlet openings therein, theside edges of said pockets in said collector electrode having electricfield forming surfaces of arcuated cross-section configuration, saidpockets in said driving electrodes and said pockets in said collectorelectrodes being opposed to each other, said inlet openings of saidpockets in said collector electrodes disposed downstream of said gapspaces formed between adjacent driving electrodes; said sorptionelectrodes being rod-shaped having a radius of curvature in thetransverse cross-section smaller than that of said field formingsurfaces of said collector electrodes and disposed downstream of thecenters of said gap spaces.

8. A two-stage type of electric dust arrester as defined in claim 6,further characterized in that the sorption electrodes are disposed inthe proximity of a plane tangential to said electric field formingsurfaces of arcuated cross-section configuration provided along the sideedges of said pockets in said collector electrodes.

9. A two-stage type of electric dust arrester as defined in claim 6,further characterized in that the polarity of the electric potential atsaid collector electrodes is the same as the polarity of the electricpotential at said sorption electrodes.

10. A dust arrester as defined in claim 6, further characterized by ahigh voltage AC source connected across said driving electrodes and saidcollector electrodes.

11. An electric dust arrester having a charging stage and a collectingstage arranged in succession within a chamber defined by a casing, saidarrester characterized by said charging stage having a pair of chargingelectrodes spaced apart laterally of the path of flow of dust throughsaid chamber; said collecting stage having a collecting electrodealigned with the space between said charging electrodes in the directionof movement of dust through said chamber; said collecting electrodehaving a pocket extending lengthwise thereof, said pocket having an openface directed toward said charging electrodes; and a high voltage DCsource of electrical energy connected to said charging and collectingelectrodes for creating a field to accelerate dust particles as theymove between said charging and collecting electrodes and for attractingthe particles into said pocket of said collecting electrode.

12. An electric dust arrester having a charging stage and a collectingstage arranged in succession within a chamber defined by a casing, saidarrester characterized by said charging stage having a plurality ofcharging electrodes spaced apart laterally of the path of flow of dustthrough said chamber; a plurality of opposite electrodes positioneddownstream of said charging electrodes; said collecting stage having aplurality of spaced apart driving electrodes therein positioneddownstream of said charging and said opposite electrodes; a plurality ofcollecting electrodes aligned with the space between said drivingelectrodes in the direction of movement of dust through said chamber;said collecting electrode having a pocket extending lengthwise thereof,said pocket having an open face directed toward said driving electrodes;and a high voltage DC source of electrical energy connected to saidcharging, opposite, driving and collecting electrodes for creating afield to accelerate dust particles as they move through said chamber andfor attracting the particles into said pocket of said collectingelectrode.

13. The dust arrester of claim 12 wherein said DC source includes anegative terminal and a positive terminal, said negative terminal beingconnected to said charging and driving electrodes and said positiveterminal being connected to said opposite and collector electrodes.

14. The dust arrester of claim 13 and further including sorptionelectrodes positioned in said pockets at the open face thereof saidsorption electrodes being connected to said positive terminal.

1. A two-stage type of electric dust arrester comprising a chargingstage and a dust collecting stage arranged in succession within a casingfrom an inlet of said casing towards an outlet thereof, characterized bythe provision of: a. a collector electrode disposed downstream of a gapspace formed between adjacent driving electrodes in said collectingstage, said collector electrode having a pocket formed therein extendingin the lengthwise direction, the inlet opening of said pocket beingdirected towards said gap space, and b. a high voltage DC source forestablishing an electric field such that charged dust particles aredriven in said electric field from said driving electrode toward saidinlet opening of said pocket in said collector electrode.
 2. A dustarrester as defined in claim 1, further characterized by coronadischarge means in said charging stage, said corona discharge meansincluding a plurality of spaced apart rod-shaped electrodes each havinga body of angle-shaped transverse cross-section, the apex edges of saidangle-shaped body being directed toward said inlet of said casing, therear edges of said angle-shaped bodies being formed with sharp tips; anda plurality of opposite electrodes disposed downstream of said coronadischarge electrodes.
 3. A dust arrester as defined in claim 2, furthercharacterized in said opposite electrodes having passageway means formedadapted for connection to a coolant source.
 4. A dust arrester asdefined in claim 1, further characterized in corona discharge electrodesdisposed in front and rear stages in said charging stage along the flowpath of dust containing gas throUgh said casing and opposite electrodespositioned between said front and rear stages of said corona dischargeelectrodes.
 5. A dust arrester as defined in claim 1, furthercharacterized in that said driving electrodes and said collectorelectrodes are formed with pockets extending in their lengthwisedirection; the side edges of said pockets providing electric fieldforming surfaces of circular cross-sectional configuration, said pocketsin said driving electrodes having inlet openings therein directed towardsaid collector electrodes, and said pockets in said collector electrodeshaving inlet openings disposed downstream of said gap space formedbetween said adjacent driving electrodes.
 6. A two-stage type ofelectric dust arrester comprising a charging stage and a dust collectingstage arranged in succession within a casing from an inlet of saidcasing towards an outlet thereof, characterized by the provision of: a.a plurality of rod-shaped collector electrodes disposed downstream of aplurality of rod-shaped driving electrodes said driving electrodes beingspaced apart having gap spaces formed therebetween, said collectorelectrodes having pockets formed therein extending in the lengthwisedirection; said pockets having inlet openings directed toward said gapspaces, b. rod-shaped sorption electrodes positioned at said inlets tosaid pockets of said collector electrodes; and c. a high voltage DCsource having a negative terminal connected to said driving electrodesand a positive terminal connected to said collector electrodes.
 7. Adust arrester as defined in claim 6, further characterized in that saiddriving electrodes are formed with pockets extending in their lengthwisedirection, said pockets having inlet openings therein, the side edges ofsaid pockets in said collector electrode having electric field formingsurfaces of arcuated cross-section configuration, said pockets in saiddriving electrodes and said pockets in said collector electrodes beingopposed to each other, said inlet openings of said pockets in saidcollector electrodes disposed downstream of said gap spaces formedbetween adjacent driving electrodes; said sorption electrodes beingrod-shaped having a radius of curvature in the transverse cross-sectionsmaller than that of said field forming surfaces of said collectorelectrodes and disposed downstream of the centers of said gap spaces. 8.A two-stage type of electric dust arrester as defined in claim 6,further characterized in that the sorption electrodes are disposed inthe proximity of a plane tangential to said electric field formingsurfaces of arcuated cross-section configuration provided along the sideedges of said pockets in said collector electrodes.
 9. A two-stage typeof electric dust arrester as defined in claim 6, further characterizedin that the polarity of the electric potential at said collectorelectrodes is the same as the polarity of the electric potential at saidsorption electrodes.
 10. A dust arrester as defined in claim 6, furthercharacterized by a high voltage AC source connected across said drivingelectrodes and said collector electrodes.
 11. An electric dust arresterhaving a charging stage and a collecting stage arranged in successionwithin a chamber defined by a casing, said arrester characterized bysaid charging stage having a pair of charging electrodes spaced apartlaterally of the path of flow of dust through said chamber; saidcollecting stage having a collecting electrode aligned with the spacebetween said charging electrodes in the direction of movement of dustthrough said chamber; said collecting electrode having a pocketextending lengthwise thereof, said pocket having an open face directedtoward said charging electrodes; and a high voltage DC source ofelectrical energy connected to said charging and collecting electrodesfor creating a field to accelerate dust particles as they move betweensaid charging and collecting electrodes and for attracting the particlesintO said pocket of said collecting electrode.
 12. An electric dustarrester having a charging stage and a collecting stage arranged insuccession within a chamber defined by a casing, said arrestercharacterized by said charging stage having a plurality of chargingelectrodes spaced apart laterally of the path of flow of dust throughsaid chamber; a plurality of opposite electrodes positioned downstreamof said charging electrodes; said collecting stage having a plurality ofspaced apart driving electrodes therein positioned downstream of saidcharging and said opposite electrodes; a plurality of collectingelectrodes aligned with the space between said driving electrodes in thedirection of movement of dust through said chamber; said collectingelectrode having a pocket extending lengthwise thereof, said pockethaving an open face directed toward said driving electrodes; and a highvoltage DC source of electrical energy connected to said charging,opposite, driving and collecting electrodes for creating a field toaccelerate dust particles as they move through said chamber and forattracting the particles into said pocket of said collecting electrode.13. The dust arrester of claim 12 wherein said DC source includes anegative terminal and a positive terminal, said negative terminal beingconnected to said charging and driving electrodes and said positiveterminal being connected to said opposite and collector electrodes. 14.The dust arrester of claim 13 and further including sorption electrodespositioned in said pockets at the open face thereof said sorptionelectrodes being connected to said positive terminal.